Eat your greens!
Some researchers at the Washington University School of Medicine put some mice on a year-long supplementation of Nicotinamide mononucleotide, a compound naturally occurring in many green vegetables. They found (cite) that it was converted to NAD+, and that the supplement “effectively mitigates age-associated physiological decline in mice.” Those last two words are key, given that you, gentle reader, are not a murid. Many more things fail to translate from mice to men than do, even when it seems so clear that they should. Mice are a good model in many ways, but still very different from us in important ways.
That said, you still should eat your vegetables. There is plenty of evidence from human studies for that. Nicotinamide mononucleotide will not be the last miracle compound found in broccoli, chard, and avocados. Eat the vegetables that aren’t green, also.